UNIVERSITY OF SOUTH AUSTRALIA SCHOOL OF PHYSICS & ELECTRONIC SYSTEMS ENGINEERING APPLIED PHYSICS 1 / PHYSICS 1S QUIZ 3 Time: 20 minutes
Marks: 15 Name ..................................................................................................... QUESTION (1 mark per question)
1.
For a mass attached to a spring on a horizontal frictionless surface, the time for one complete oscillation will depend on (A) the value for the acceleration due to gravity, (B) the distance the mass was originally pulled from its equilibrium position, (C) the maximum speed of the oscillating mass, (D) the value of the mass.
2.
A wave pulse is travelling to the right on a heavy string attached to a light string as shown below. When the wave reaches the boundary between the two strings it will be é¨
é¨
(A) (B) (C) (D)
partially transmitted and partially reflected, and no inversion will occur, partially transmitted and partially reflected, and the reflected pulse will be inverted, entirely transmitted, and no inversion will occur, entirely reflected, and no inversion will occur.
3.
If the tension on a guitar string is increased by a factor of 3, the speed of waves on the string is changed by a factor of (A) 9, (B) 3, (C) , (D) .
4.
What is the intensity of sound in W/m2 from a rock band with a sound level of 120 dB? (I = 10–12 W/m2.) 0
5.
(A)
1 W/m2.
(B)
1.2 W/m2.
(C)
10 W/m2.
(D)
12 W/m2.
As a train starts from rest and then accelerates down the track toward you, the speed of the sound waves coming toward you will be (A) lower than the normal speed of sound in air, (B) equal to the normal speed of sound in air, (C) some constant factor greater than the normal speed of sound in air, (D) continually increasing.
ANSWER
– 2 –
PLEASE TURN OVER
Problem1 (3 marks) State with reasons, how the following properties of a simple harmonic oscillator are affected by doubling the amplitude: (a) frequency, (b) total mechanical energy, and (c) maximum acceleration. ................................................................................................................................................................................. ................................................................................................................................................................................. ................................................................................................................................................................................. ................................................................................................................................................................................. ................................................................................................................................................................................. ................................................................................................................................................................................. ................................................................................................................................................................................. ................................................................................................................................................................................. .................................................................................................................................................................................
Problem 2 (4 marks) A sinusoidal wave is described by y = 0.25sin(2.0x – 40t) where x and y are in meters and t is in seconds. What is (a) the amplitude (0.5 mark), (b) the wavelength (1 mark), (c) the frequency (1 mark), (d) the speed of the wave (1 mark), and (e) the direction of wave travel (0.5 mark)? ................................................................................................................................................................................. ................................................................................................................................................................................. ................................................................................................................................................................................. ................................................................................................................................................................................. ................................................................................................................................................................................. .................................................................................................................................................................................
................................................................................................................................................................................. ................................................................................................................................................................................. .................................................................................................................................................................................
Question (3 marks) If a long rope is hung from a ceiling and waves are sent up the rope from its lower end, the waves do not ascend with constant speed. Does the wave speed decrease or increase up the rope? Explain. ................................................................................................................................................................................. ................................................................................................................................................................................. ................................................................................................................................................................................. ................................................................................................................................................................................. ................................................................................................................................................................................. ................................................................................................................................................................................. ................................................................................................................................................................................. .................................................................................................................................................................................